1. Field of the Invention
The present invention relates to a novel vibrator system using an ultrasonic motor as the power source, as well as to a vibrotherapeutic device using the vibrator system.
2. Description of the Prior Art
Local vibrostimulation to human body is effective in the shortening of sleep latency to treat insomnia, as well as in the relieving of pains in myalgia, lumbago, arthritis, rheumatism and stiffness in the shoulder.
In typical conventional vibrotherapeutic device, a vibratile plate is actuated by using a conventional-type magnetic motor in combination with an eccentric weight or a cam mechanism. Such vibrotherapeutic device has the drawbacks that it becomes long and unwieldy in a direction of the rotary axis of the motor: that it attains an unsatisfactorily low energy efficiency because it yields an small output energy with respect to the inputted energy; and that it does not adequately work when the load descend the vibratile plate to restrict the operative range of the cam mechanism.
To avoid these drawbacks of conventional vibrotherapeutic device, Japanese Patent Laid-Open Nos. 209,284/85 (Y. ENDO et al), 216,870/85 (Y. ENDO et al) now U.S. Pat. No. 4,697,581 and 5,359/87 (K. MASAKI) now U.S. Pat. No. 4,710,655 propose a system wherein a magnetic coil placed in parallel with a coil or a vibratile member is intermittently energized with an alternating current through a charge/discharge circuit using a thyristor and a capacitor in combination and the resultant attraction and repulsion are used to generate a vibration, while Japanese Patent Publication No. 10,145/86 (Y. ENDO) proposes a system to vibrostimulate human body wherein an amplified signal from an audio frequency oscillator is used to actuate a sound generating means such as loudspeaker.
These proposals have, however, proved unsuccessful: The former system using a coil and a charge/discharge circuit frequently encounters the drawback that it consumes a large amount of electric energy. While the latter system using a sound generating means such as loudspeaker has the advantage that its vibration frequency is easily changeable, but becomes unwieldy and attains an unsatisfactory low energy efficiency because it requires a large-scale power source in order to obtain a sufficiently strong sound pressure on the vibratile plate that is in contact with human body.